Known magnetron-based radar devices use the amplitude information associated with an echo or return pulse in an attempt to detect a target. While amplitude-based detection is suitable for some circumstance, it is not preferable for all circumstances particularly when the target is small, when there is a large amount of clutter relative to the target strength, or both.
Phase-based detection generally provides enhanced levels of target detection allowing for easier recognition of a target from surrounding clutter. The prior art includes phase-based detection radar systems, referred to as coherent radar systems (and include coherent-on-receive systems), which provide enhanced levels of target detection based on the phase information associated with the return pulse. However, the coherence of these prior art systems is largely attributable to hardware techniques in which the received phase is directly or indirectly related to the phase of the transmitter or some other host-radar reference. The cost of many of these coherent radar systems can range from four to eight million dollars, while the cost of non-coherent magnetron-based radar system can run as little as five thousand dollars. The magnitude of the cost differential is due, at least in part, to the use of costly transmitter/receiver technologies that are used to obtain phase coherence. There is a need for a low-cost alternative to achieving coherence that provides enhanced target detection.
Prior art embodiments of coherent radar devices include, for example, fully-coherent radar devices and coherent-on-receive radar devices. Known embodiments of fully-coherent radar device include transmit and receive oscillators that are in a fixed-phase relationship with one another. The transmitter and receiver of these embodiments either share an oscillator or use two separate oscillators locked to the same source. By contrast, known embodiments of coherent-on-receive devices use a substantially stable reference oscillator to correct phase differences at the receiver, based on phase differences from the transmitter. Fully-coherent radar devices and coherent-on-receive devices are both examples of a coherent radar device.
Known techniques used to achieve coherence of a simple, magnetron-based, non-coherent radar device require that the hardware of the radar device be modified. Invasive hardware modifications, including the addition of components and signal paths, may be cost-prohibitive. There are no known examples of a system for non-invasive modifications that provide coherence of return pulses received by a non-coherent radar device. However, there is a need for a device that can be coupled to a magnetron-based or other non-coherent radar device to enhance detection of a target and techniques for achieving coherence. Overcoming the disadvantages present in the prior art, various embodiments of the invention comprise a system, device and/or method for cohering the intermediate frequency signal of a radar device for enhancing levels of target detection.